Two adolescent DTP booster vaccines are currently available—BOOSTRIX™ & ADACEL™ [1]. Both vaccines contain diphtheria toxoid, tetanus toxoid and acellular pertussis antigens. They are also available in combination with inactivated poliovirus (BOOSTRIX POLIO™ and ADACEL POLIO™). All of these vaccines include an aluminium salt adjuvant.
In general these vaccines are known as TdaP vaccines, in contrast to pediatric DTaP vaccines. A common feature is that, relative to their pediatric counterparts, they have lower antigen doses e.g. the diphtheria toxoid content of BOOSTRIX™ is 10-fold lower than in the INFANRIX™ products, and in ADACEL™ it is 7.5-fold lower than in DAPTACEL™. Moreover, the ratio of antigenic components is also altered. In particular, the ratio of diphtheria and tetanus toxoids is 2.5:1 in the INFANRIX™ products but is 1:2 in the BOOSTRIX™ product, and is 3:1 in the DAPTACEL™ product but is 1:2.5 in the ADACEL™ product. Thus these booster vaccines show a large reduction in the dose of diphtheria toxoid, both in absolute amounts and also relative to the tetanus toxoid content. Some of the pertussis components also differ from the levels seen in the pediatric counterparts, but the levels of the poliovirus antigens are the same in both the pediatric and adolescent vaccines. Based on public information the compositions are as follows:
DTPa(1)IPV(3)VolumeAl+++Boostrix ™2.5 Lf5 Lf8/8/2.5—0.5 ml≦0.39 mg  Boostrix 2.5 Lf5 Lf8/8/2.540/8/320.5 ml 0.5 mgPolio ™Adacel ™  2 Lf5 Lf2.5/5/3(2)—0.5 ml0.33 mgAdacel   2 Lf5 Lf2.5/5/3(2)40/8/320.5 ml0.33 mgPolio ™Notes:(1)Pa dose shows amounts of pertussis toxoid, then FHA, then pertactin (μg).(2)Adacel's Pa components also contain 5 μg fimbriae types 2 and 3.(3)IPV dose shows amounts of type 1, then type 2, then type 3 (measured in DU).
It is an object of the invention to provide further and improved TdaP vaccines suitable for human use as a booster in adults, adolescents and children aged four years and older who have previously received childhood immunisation.